Final answer:
The Voges-Proskauer test uses alpha-naphthol and potassium hydroxide to detect the presence of acetoin, indicating if bacteria use the butanediol fermentation pathway for glucose.
Step-by-step explanation:
The Voges-Proskauer (VP) test involves two primary reagents: alpha-naphthol and potassium hydroxide (KOH). The test is designed to detect the presence of certain fermentation end products, specifically acetoin, in bacterial cultures that have been incubated with glucose.
Acetoin is an intermediate in the butanediol fermentation pathway utilized by some bacteria when fermenting glucose. If acetoin is in the culture medium, the addition of VP reagents will result in a characteristic reddish-brown color, indicative of a positive VP test result. This indicates that the bacteria are using a metabolic pathway that produces butanediol and acetoin, among other substances.